1. Field of the Invention
The present invention relates to a method of manufacturing a coated metal plate which results in the facile control of the gloss of the coating and prevents the phenomenon of heat blocking from the heat treatment during a lamination of the coated metal plate. The present invention also relates to the coated metal plates prepared by such a process and laminates comprising such coated metal plates.
2. Discussion of the Background
Various composite laminates are known wherein a metal sheet is laminated on a thermoplastic synthetic resin sheet. U.S. Pat. No. 4,508,425 discloses a mirror manufactured by plating chromium on one surface of a metal sheet bonded to a composite sheet, made up of a synthetic resin sheet and the metal sheet, to form a mirror surface. The mirror may be worked to a desired shape and may be formed with a decorative pattern.
U.S. Pat. No. 4,560,623 discloses a specular product of bronze-like tone particularly suitable for use as a decorative material. The specular product uses, as a substrate, a composite board comprising a synthetic resin sheet and metal sheets laminated thereon, and includes a nickel deposit plated on the metal sheet and a specular film of Sn-Ni alloy electroplated on the nickel deposit using a specific electroplating bath.
Such laminates are useful for a number of architectural applications, because the laminates combine light weight with high strength. These laminates may be used as finished surfaces for all or portions of the interior or exterior surfaces of a building.
It is also desirable to produce metal-resin composite laminates in a wide variety of colors and with a high degree of gloss. It is also desirable that such metal-resin composite laminates exhibit good weathering resistance and be able to be bent to a sharp angle without cracking of the coating on the exposed surface of the metal. However, when metal sheets are coated with conventional polyvinylidene fluoride (PVDF) paints, the coated plates exhibit a phenomenon known as heat blocking upon subsequent lamination with the resin layer. This heat blocking phenomenon seriously detracts from the aesthetic appeal of the finished plate. In addition, use of conventional PVDF paints results in coatings which have a gloss within a fairly narrow range, 25 to 35%.
Thus, there remains a need for coated metal sheets in a wide variety of colors and a wide range of gloss, which do not experience heat blocking on lamination and exhibit excellent weathering resistance. There also remains a need for laminates in a wide variety of colors and wide range of gloss, which can be bent to a sharp angle without cracking of the coating. There also remains a need for methods for preparing such metal sheets and such laminates.